Technical Field
The present disclosure relates to a vascular stent for implanting within a vessel of a living body such as a blood vessel, trachea or bile duct to scaffold the lumen of the vessel from the inside.
Background Art
Heretofore, in a vessel of a living body, particularly in the case of stenosis occurring in a blood vessel such as a coronary artery, percutaneous transluminal angioplasty (PTA) has been performed in which a balloon catheter is used to expand the stenosed portion from the inside to improve blood flow.
The site once stenosed, however, is known to have a high probability of restenosis or acute occlusion due to intimal dissection even after PTA. To prevent such acute occlusion or restenosis, a tubular shaped stent is implanted at the site following PTA. The stent used herein is in a contracted state when introduced into a blood vessel, and subsequently expanded in diameter so as to be deployed at the intended site to scaffold the vessel from the inside to maintain an open state.
This variety of vascular stent is inserted to the target lesion within the blood vessel in the contracted state along with a stent delivery device such as a catheter. Once the vascular stent is inserted at the lesion, an expanding mechanism such as a balloon provided in the stent delivery device is used for expansion thereof from the contracted state into an expanded state and the blood vessel is scaffolded in an expanded state.
Thus, all conventionally used and heretofore proposed vascular stents have been configured to change from a contracted state to an expanded state.
Vascular stents have been proposed which are configured to enable changing from a contracted state to an expanded state in which ring-shaped strands having zig-zag bends are connected by a connecting part as a tubularly shaped (PLT 1 and 2).
Furthermore, the applicant of the present application has proposed a vascular stent configured to have a single flow path from one side to another side in which a strand made of a biodegradable polymer is bent so as to have successively alternating straight portions and bent portions to form a tube-forming element, a plurality of which are combined together to each form a portion of a tube (PLT 3 and 4).